The mineral calcium forms an important part of proper nutrition. Calcium is essential for bone and tooth formation. Approximately 99 percent of the calcium in the body is stored in bones and teeth, while the remaining 1 percent is present in the blood and soft tissues as circulating calcium (generally in the form of Ca+2 ions). The circulating calcium is essential for proper muscular contraction, blood clotting, and nerve transmission functions. In addition to their structural role, bones provide an emergency supply of circulating calcium.
Osteoporosis is a widespread problem, afflicting approximately twenty million women and five million men in the United States to some degree. Post-menopausal women typically lose about 0.7 to 2 percent of their bone mass per year, while men lose about 0.5 to 0.7 percent. Consequently, between the ages of 45 and 70, women and men can lose about 30 and 15 percent, respectively, of their skeletal mass. In the United States more than one million bone fractures occur annually in women 45 years or older; in about 70 percent of these cases, osteoporosis plays a significant role. There are approximately 190,000 hip fractures annually in the United States; hip fractures are the second leading cause of death in people 47-74 years of age. More recent studies have suggested that reduced calcium intake in children may result in increased risk for osteoporosis later in life.
Dietary calcium supplementation and fortification is recognized in the health field as a convenient and safe approach for addressing calcium deficits. The Recommended Dietary Allowances (RDA's) for calcium by the National Academy of Sciences are 1,200 mg/day for adults 51+ years old; 1,000 mg/day for adults 19-50 years old; 1,300 mg/day for children 9-18 years old; 800 mg/day for children 4-8 years old; and 500 mg/day children 1-3 years old. The US Daily Value (DV) for calcium is 1000 mg/day for all individuals; this reference value is typically used to establish nutritional calcium levels in food products. The Food and Drug Administration (FDA) permits foods and beverages containing at least 100 mg calcium per serving to be labeled as a “good source of calcium”; those containing at least 200 mg calcium per serving may be labeled as an “excellent source of calcium.”
However, many conventional dietary sources of calcium contain lower than desired levels of calcium. Simply increasing the amount of calcium using conventional fortification techniques to provide more nutritionally desirable levels often unfavorably impacts the food product's pH, flavor, texture, appearance, and/or cost. Another problem is that many conventional dietary sources of calcium have low solubility or dispersability in water and tend to precipitate in aqueous solutions, forming turbid fluids and/or sediments which can impart undesirable chalky or gritty attributes in beverages. Such quality defects can decrease consumer acceptance and limit consumption, thereby reducing the nutritional benefits afforded by such calcium-containing products.
Among the conventional calcium citrate compounds most commonly used in foods, crystalline tricalcium dicitrate (i.e., tricalcium citrate or “TCC”; calcium:citrate mole ratio of 3:2) has limited utility in beverage applications since it is virtually insoluble in water. The TCC ingredient most commonly used in food fortification is crystalline TCC tetrahydrate. Although this material contains a high level of calcium (about 21 percent), it only provides about 6 mg of soluble calcium per fluid ounce of water at room temperature due to its low solubility (i.e., less than 0.1 percent in water at room temperature); this level of fortification would provide only about 5 percent of the U.S. DV for calcium in soluble form; simply attempting to add greater amounts to water would result in immediate precipitation. Other sparingly soluble calcium citrates like crystalline monocalcium dicitrate (i.e., monocalcium citrate or “MCC”; calcium:citrate mole ratio of 1:2) and crystalline dicalcium dicitrate (i.e., dicalcium citrate or “DCC”; calcium:citrate mole ratio of 2:2) also have limited utility due to slow dissolution, incomplete dispersion, or undesirable sedimentation.
U.S. Pat. No. 4,851,221 describes a dry powdered premix of citric acid and calcium hydroxide in a mole ratio of between about 0.6 to about 1.5, which is combined directly with a potable liquid to make a solution reported to have enhanced calcium bioavailability. The premix, after being dissolved in water, is reported to form calcium citrate precipitates within several hours after dissolution in water unless the pH is below about 3.5. The relatively low pH value required to avoid precipitation of the calcium citrate is a significant limitation on the usefulness of the premixes described therein. Moreover, calcium hydroxide is strongly alkaline and can cause degradation and/or discoloration of many commonly used food ingredients (especially if there is exposure to moisture during storage), thereby leading to a poor quality product with a reduced shelf life.
U.S. patent application 2002/0122866 describes a method and apparatus for producing a calcium fortified liquid beverage by forming a solution containing a soluble calcium salt of an organic acid and immediately blending with a liquid beverage in a continuous manner to avoid formation and precipitation of insoluble salts. No soluble calcium citrate or other salts in dried form were disclosed.
Calcium salts of organic acids have been used in food processing. U.S. Pat. No. 5,208,372 describes a solid calcium citrate anti-caking agent that is a water insoluble crystalline calcium citrate salt at ambient temperature having a calcium:citrate ratio of 2.5:2 to 2.95:2, and which also is said to be useful in powdered soft drinks sweetened with fructose. U.S. Pat. No. 5,219,602 describes an aqueous dispersion containing the crystalline calcium citrate salt having a calcium:citrate ratio of 2.5:2 to 2.95:2, which can be used to opacify and whiten food compositions. The insoluble crystalline calcium citrate salts described in these patents are formed by combining a calcium compound with citric acid in water and allowing adequate time for the reaction product to solidify before drying.
U.S. Pat. No. 6,235,322 describes highly soluble and stable mineral supplements containing calcium and magnesium. In particular, a fiber-free calcium/magnesium material is provided by solubilizing a calcium/magnesium mixture in an aqueous acid solution and drying the reaction product. The use of magnesium is reported to increase calcium solubility and help to provide adequate time for solutions to solidify prior to freeze drying or tray drying. Numerous specific examples of salts other than calcium citrates are provided.
As can be appreciated, there remains a need for approaches for fortifying instant and ready-to-drink (RTD) beverages with safe, convenient, and compatible forms of nutritional high-calcium salts that can provide calcium at high dietary levels and which provide improved solubility and increased shelf life stability. The present invention fulfills these, as well as other needs and objectives, as will be apparent from the following description of embodiments of the present invention.